This invention relates to a method for treating patients with obstructed arteries, and in particular, for preventing a renarrowing after standard therapies, an event which afflicts as many as 45,000 patients a year in the United States.
In 1964, a breakthrough in treating arterial disease occurred when a non-surgical technique to unblock vascular lumens became available. Known as percutaneous transluminal angioplasty (PTA), angioplasty today has become an accepted therapy for peripheral and coronary vascular disease, not only in the U.S., but internationally. The widespread use of PTA for the management of vascular disease is due to, among other factors, advances in percutaneous catheter technology and a high level of acceptance by patients of non-operative procedures.
The development of the balloon catheter in 1974 significantly contributed to the efficacy of PTA. In balloon angioplasty, a catheter equipped with a dilatable balloon is threaded intravascularly to the site of atherosclerotic narrowing of the vessel. Inflation of the balloon with concomitant compression of atheroma enlarges the atherosclerotic narrowing, and enlarges the lumen by stretching the vessel wall.
Complications can result from transluminal angioplasty. One serious complication is that of restenosis which frequently accompanies the various methods of angioplasty for treating coronary and non-coronary vasculature. Restenosis is the renarrowing of the vessel after angioplasty, and often requires multiple angioplastic procedures.
At present, there is no effective means for preventing restenosis following angioplasty, atherectomy or the newer modes of laser therapy for enlarging stenotic vessels.
In the United States, it is estimated that of the 300,000 patients yearly who undergo procedures involving angioplasty or atherectomy to remove stenotic lesions from coronary arteries, from 15% to 30% of those patients exhibit restenosis. Several studies document a restenosis rate of 25% to 35% within the first year following coronary angioplasty, with the vast majority of patients requiring repeat procedures within 6 months. Furthermore, the restenosis rate for angioplasty of the smaller, peripheral arteries also occurs at a significant rate.
Thus, a drawback of angioplasty is the frequent complication of restenosis, requiring a patient to undergo one or more repeat angioplastic procedures, which are costly and subject the patient to the risks associated with any medical procedure.
Another problem associated with angioplasty is crimping and puckering of the thin-walled, small diameter flexible catheters as they are pushed through twisting and turning sections of the vascular system. Similar to a thread being pushed through a tube, a thin-diameter, flexible catheter frequently crimps or kinks as it is being pushed through vascular lumen, delaying the procedure. Despite advances in catheter technology, the physician still faces the difficult and time-consuming task of manipulating the catheter when such crimping occurs.
Accordingly, there is a need for (a) a method to prevent the necessity for repeated lumen-enlarging procedures following angioplasty, and (b) a catheter that will not crimp or pucker when being pushed through twisting and turning sections of the vasculature system.